The present invention relates to a single use camera, which is previously loaded with a photographic film, namely a 135 size roll film, and into which simple exposure mechanisms such as a taking lens, a shutter, and a film advancing mechanism are built. The present invention relates especially to a single use camera of which film-advancing mechanism and also previous film loading are driven by a built-in motor and relates particularly to a construction of camera casing from which exposed film can be removed easily without destroying any part of camera body to enable manufacturers to recycle cameras without any additional parts or modifications for recycling.
Single use cameras are now very popular on the market today. They are loaded with an unexposed film previously and the film is to be wound back after each exposure to a removable cartridge also provided in the camera, and purposed to enable users to take pictures whenever they like without buying expensive cameras. However, these single use disposable cameras are not recyclable due to its body construction, from which exposed film cannot be removed unless a part of the body is destroyed. Further more, the way of previous loading of film into the camera is quite complicated.
As disclosed in U.S. Pat. Nos. 4,884,087 and 4,972,649 single use disposable cameras are assembled usually by the steps of winding a film withdrawn from a film cartridge (patrone) in a roll in a dark room; loading the rolled film and the film cartridge in respective receiving chambers formed in a main body section of the single use camera; fitting a back cover to the main body so as to close light-tightly the single use camera; and sealing the single use camera so that it cannot be opened. To carry out the steps mentioned above, it is necessary to provide a special film loading device which is very complicated in mechanism and also necessary for all the steps to be done in a dark room. As is well known, such a dark room film handling is quite troublesome.
Further more the back door of the conventional single use camera is sealed light-tightly, so unless the light-tight film casing is destroyed to open the same the exposed film cannot be removed out of the camera. These two things, namely pre-winding film in a roll using the special film loading device in a dark room and the light-tight film casing which must be destroyed for removing exposed film out of the camera unable manufacturers or photofinishers to recycle the single use camera easily. For ordinary users it is impossible to follow the steps as mentioned above. So the conventional single use cameras on the market today are not recyclable, and only some of the components can be reused for a new single use camera.
If a single use camera, like the single use camera of the present invention, has a built-in motor by which the film can be easily pre-wound over the film pre-winding take-up spool in daylight without any help of special jig like film loading device from the outside of the camera, the single use camera can be easily loaded again with a new film in daylight also by using the motor. And if a sort of back door is provided with the single use camera, the exposed film can be easily removed out of the camera without destroying any part of the camera body, and the manufacturers or photofinishers can recycle such single use cameras without any problem.
In the case of the single use camera of the present invention, the manufacturers or photofinishers need not provide such a costly instrument like film loading device to be used in a darkroom and need not destroy any part of the single use camera, and easily can re-load the single use cameras with new films very cheaply in daylight. Even for individual users it can be done without any special tooling.
Further more if the same built-in motor can wind the film up automatically after each exposure eliminating manual film winding mechanism, the handling of the single use camera will be far much more convenient in comparison with conventional manual winding single use cameras.
It is, therefore, an object of the present invention to provide a single use camera which has a built-in motor with which film pre-winding and film-reloading can be made quite easily without using any kind of mechanical help from the outside of the camera.
It is another object of the present invention to provide a single use camera which has a built-in motor with an automatic film winding mechanism, which is a specially designed simple mechanism for switching the film driving directions from pre-winding to ordinary film advance winding or reverse way, and also for controlling the sprocket wheel and shutter charging and releasing.
Still another object of the present invention is to provide a single use camera that has a sort of back door, which can be opened easily for removing the exposed film out of the camera without destroying any part of the camera.
To achieve the above objects, the single use camera according to the present invention comprises a main body having an exposure opening; a motor built-in the main body to pre-wind film or to wind back film; a film pre-winding take-up spool around which unexposed film is rolled up by the motor disposed on one side of exposure opening in the main body; a removable film cartridge having a film winding spool therein, into the slot of which the end of the film is inserted and fixed, disposed on the other side of exposure opening in the said main body; a film winding member which is driven by the motor built in the said main body for pre-winding the unexposed film around the film pre-winding take-up spool and for winding back exposed frames into the film cartridge; a shutter-sprocket wheel control means which controls the exposure and the film winding member; a back cover which is fixed to the main body from the rear side with a hinge and can be closed and opened by a lock-unlock means; and a front cover to be fixed onto the main body from the front side to make the whole camera body into a light-tight casing together with the closed back cover.
According to the present invention, a new unexposed film is pre-wound around the film pre-winding take-up spool, and the unexposed film is wound back around the film spool of the film cartridge by one frame after each exposure. And the motor built in the main body drives both the pre-winding of the unexposed film and the winding back of the exposed film. When the exposure of all frames of the film has been completed, the film is fully wound back into the film cartridge, and by opening the back door the film can be removed from the single use camera in daylight. In the case of the single use camera of the present invention, it is not necessary to destroy any part of the single use camera to remove the exposed film out of the camera.
Generally speaking conventional 35 mm compact cameras with motorized film driving use the film winding to rotate the sprocket wheel to count the perforations and stop the motor running after one frame of the film has been advanced. Simultaneously the rotation of the sprocket wheel is used for shutter charging. Consequently after one shutter releasing, and while the film is moving, the sprocket wheel is always rotating coupling with the film running and at the same time shutter is being charged also coupling with the sprocket rotation. Therefore in the case of conventional 35 mm motor driven compact cameras for rewinding the film after the entire film has been exposed or for pre-winding an unexposed film, it is always necessary to provide a switch to change the rotation of the motor rotation or to switch the direction of film running with a rather complicatedly constructed clutch mechanism having the sprocket wheel be free from shutter charging. Otherwise if the film running direction is switched from picture taking to pre-winding or rewinding direction, the sprocket wheel will be stuck because of shutter charging mechanism, which does not move in the direction of pre-winding or rewinding of the film.
In the single use camera of the present invention the built-in motor is used for pre-winding the unexposed film withdrawn from the film cartridge around the film pre-winding take-up spool and also for winding back the exposed film after each exposure into the film cartridge. Therefore the direction of the built-in motor rotation should be different between the pre-winding of the unexposed film and winding back the exposed film into the film cartridge, and it is necessary to switch the direction of the built-in motor rotation for each case.
To accomplish such switching of the direction of motor rotation, the single use camera of the present invention uses a method of changing the position of the battery upside down in the battery chamber so that electricity flows from one way to the other depending on the positions of the poles of the battery in the battery chamber, and the directions of motor rotation can be switched also one direction to the other. To use the switching method as explained above, the battery chamber of the single use camera of the present invention has a specially designed battery chamber which has an ordinary spring contact at one side and two metal contacts of different kind on the other side, and by selecting one of the two metal contacts depending on the polarity of the battery inserted in, the direction of electricity flow is changed accordingly.
By changing the direction of the motor rotation, the direction of film running also changes from pre-winding direction, namely direction of film running out of the film cartridge to the film pre-winding take-up spool, to film wind-back direction, namely direction of film running back into the cartridge from the film pre-winding take-up spool.
The shutter charging and film travel distance control are usually done by using a sprocket wheel, which engages with the perforations of the film. While the film is moving for pre-winding, the sprocket wheel must turn freely along with the running film perforations, and should not do any shutter charging or film travel distance control (where to stop the film running). On the contrary while the film is moving back into the film cartridge, the sprocket must turn also along with the running film perforations, but this time while film is moving the sprocket must charge the shutter for next exposure, and must stop film running after each exposure working together with the shutter charging and sprocket control means. To achieve switching of the function of the sprocket wheel according to the film running directions or the direction of the motor rotation, the single use camera of the present invention has a simple mechanism that works as a shutter charging and releasing means including a sprocket wheel, which is turned by the moving film perforations in one direction while the film is being wound back into the film cartridge, and that can make the sprocket wheel move freely in the other direction with the moving film perforations without any kind of a clutch while the film is being pre-wound up around the film pre-winding take-up spool as well. This simple shutter-sprocket wheel control means works for multiple purposes like shutter charging, shutter releasing, switching the motor on and off, having the sprocket be free from shutter charging mechanism for pre-winding the film.